1. Field of the Invention
The present invention relates to a base station controller and, more particularly, to a base station controller wherein the base station can be small-sized in order that it is to be installed in a rack of the base station and the number of boards installed in a backboard can be flexibly increased or decreased according to a subscriber capability.
2. Description of the Related Art
Generally, a private wired communication service for voice communication on a premises was provided by a private exchange (or a key phone system), and a communication service for data was provided by a LAN switch and a router using a server.
Normally, while mobile communication can provide a service almost everywhere without restricted areas, such as the premises, this service makes use of a mobile communication service system, which is charged a separate fee to wirelessly communicate in a predetermined area.
That is, when a terminal of a wired private exchange and a mobile terminal of a mobile communication service subscriber are to communicate with each other, both exchanges are connected to a public network and a call of one party is connected to the other party.
Here, the public network includes a mobile communication network and a public telephone exchange network. Accordingly, even when a wired subscriber and a mobile communication service subscriber speak over the telephone to each other in a building, they have to charge a separate fee.
Therefore, a private mobile communication service system has been developed, which enables the wired subscriber and the mobile communication service subscriber to speak over the telephone without any charge when they try to speak over the telephone in a building (here, a conventional mobile communication service system is denominated as a public mobile communication service system so as to separate it from the private mobile communication service system).
The private mobile communication service system enabled a mobile communication subscriber registered in the private mobile communication service system to provide another mobile communication subscriber registered in the private mobile communication service with a call service, or vice versa in an area where the private mobile communication service is provided without any charge, using an extension connected to a private exchange.
FIG. 1 is a view explaining a concept of public/private mobile communication services.
In order to provide the public and private mobile communication services altogether, there are provided a public/private sharing cell area 114 which is a public/private sharing communication service area, and a public/private communication service unit 112 as shown in FIG. 1.
In order to separate base stations (BTSs), a.k.a., base transceiver stations, included in the public mobile communication service system, that is, BTSs (106-1, . . . 106-k, 108-1) shown in FIG. 1 as examples from a private base station 108-k in the public/private sharing cell area 114, the private base station 108-k is denominated as a pBTS (a private BTS).
The pBTS 108-k constitutes a wireless communication line together with a mobile station (MS) 124 included in the public/private sharing cell area 114, performs a management of wireless resources, and is connected to a base station controller (BSC) of the public mobile communication service system, that is, a BSC 104-m shown in FIG. 1 through the public/private communication service unit 112.
The public/private communication service unit 112 is connected to the BSC 104-m, a public switched telephone network/integrated service digital network (PSTN/ISDN) 116, and an Internet protocol (IP) network 118 of the public mobile communication service system. The public/private communication service unit 112 performs a mobile communication service in order that the public mobile communication service and a private mobile communication service can be selectively provided to mobile stations (MSs) in the public/private sharing cell area 114, for example, an MS 124 of FIG. 1.
If the MS 124 is registered in the public/private communication service unit 112 to be provided with the private mobile communication service, the MS 124 can receive the private mobile communication service as well as the public mobile communication service.
However, if the MS 124 is not registered in the public/private communication service unit 112 to be provided with the private mobile communication service, the MS 124 can be provided with only the public mobile communication service. Also, the public/private communication service unit 112 performs a wired communication service with the PSTN/ISDN 116 and the IP network 118.
On the other hand, a difference between the private mobile communication service system and the public mobile communication service system when installing the base station (BS) and the base station controller (BSC) is that how closely the private base station (pBS) and the base station controller (BSC) can be installed.
FIG. 2 is a view showing a conceptual construction of a private mobile communication service system, which shows that a private base station 232 and a private base station controller 230 can be installed in the same place and closely in the private mobile communication service system differently from the case of a conventional public mobile communication system where the base station and the base station controller are installed separately so that needed signals are transmitted and received between them using an E1/T1 link.
Furthermore, the private mobile communication service system can have the private base station 232 and the private base station controller 230 installed in a rack, and such an installation of the private base station 232 and the private base station controller 230 in the rack can result in a reduced-cost effect in constructing the private mobile communication service system.
Furthermore, the private mobile communication service system can be small-sized in the situation that the private mobile communication service system is generally constructed in a building or the like.
FIG. 3 is a view showing a conceptual construction of a private base station controller installed in a rack.
Referring to FIG. 3, it is seen that the private base station controller is installed in a rack constructed with four shelves.
A first shelf 310 has two ACMA (ATM (asynchronous transfer mode) Cell Mux/Demux board Assembly) boards constructing an ASB (ATM Switch Block) of a BAN (BSC ATM switch Network) which provides a communication path between processors in the private base station controller and a communication path between the private base station and the public base station controller, and eight TCLA (Transcoder Control and Link board Assembly) boards constructing a TCB (Transcoder Bank) which has a vocoder, converts PCM (pulse code modulation) data to 8K QCELP/EVRC or 13K QCELP data, and QCELP (Qualcomm Code Excited Linear Prediction) or EVRC (Enhanced Variable Rate Coder) data to PCM data.
A second shelf 320 has two ACMA boards constructing an ASB of a BAN, two BHPA (BSC High Performance Processor board Assemblies) boards constructing a BMP (BSC Main Processor) which performs functions of a call processing of a private base station controller, a No. 7 signal (SS7) processing and an ATM link control, which is a main control block, two ASFA (ATM Switch Fabric board Assemblies) boards which provide a communication path between the BMP and another processor by constructing the ASB of the BAN, one HACA (Hardware Alarm Collection board Assembly) constructing an HAB (Hardware Alarm Collection Block) which collects hardware error information occurred in each block in the private base station and informs the BMP (BSC Main Processor) of the information, and one ASIA (ATM STM-1 interface board Assembly) board constructing an ALB (ATM Link Block) of the BAN.
Also, a third shelf 330 has two GCRU (GPS (global positioning satellite) Clock Receiver Unit) boards constructing an NSB (Network Synchronization clock distribution Block) which generates a network synchronization clock with a clock received from the GPS and time information and provides a needed block with the synchronization clock, three MCDA (Master Clock Distribution board Assembly) boards, two ACMA boards constructing the ASB of the BAN, and three AETA (ATM E1/T1 interface board Assembly) boards constructing the ALB.
Also, the lowest shelf 340 has two ACMA boards constructing the ASB of the BAN, and eight BHPA boards constructing an ATP (Air Termination Processor) which processes signals such as a handoff signal and a power control signal which is received together with traffic data after the call has been established and performs an RLP (Radio Link Protocol) or MAC (Media Access Control) function for the data call.
However, it is required that the private base station controller becomes small-sized in order to install the private base station and the private base station controller in a rack.
Also, in the case that the private base station controller becomes small-sized and installed in the private base station, it is required that a board is designed flexibly according to its installation place and the number of required boards is increased or decreased according to a subscriber capacity.